Information recording medium, and recording method and reproducing method thereof

ABSTRACT

An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuing application of application Ser. No.11/131,424, filed May 18, 2005, now U.S. Pat. No. 7,023,791 which is acontinuing application of application Ser. No. 09/854,557, filed on May15, 2001 now U.S. Pat. No. 6,965,555, and for which priority is claimedunder 35 U.S.C. § 120; and this application claims priority ofApplication No. 2000-145353 filed in Japan on May 17, 2000 andApplication No. 2000-252827 filed in Japan on Aug. 23, 2000 under 35U.S.C. § 119. This application is related to 11/164,985, 11/306,064 and11/306,066 filed concurrently herewith. The entire contents of all arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information recording medium, and arecording method and a reproducing method thereof, wherein theinformation recording medium is composed of a recording/reproducing areaprovided with a guide groove and a groove and a read only area formedwith a pit array, and further, the information recording medium isformed with an address information of the recording/reproducing area ona land provided between guide grooves as a land pre-pit (hereinafterreferred to LPP), and particularly, relates to an information recordingmedium enabling to be recorded and reproduced such as a DVD-RW (DigitalVersatile Disc for Re-recordable) disc, and a recording method and areproducing method thereof.

2. Description of the Related Art

Generally, in a high density recordable optical disc (hereinafterabbreviated as a recordable optical disc) such as a DVD-RW disc, whichis interchangeable with a DVD video disc and can be recorded a pluralityof times, a contents to be protected by copyright and other contentsmust be identified and prevented from illegal copying of the contents soas not to be recorded or reproduced. Basically, a DVD-Video disc is aread only disc. The DVD-Video disc is recorded with a copyrightinformation for prohibiting copying contents of the DVD-Video disc byusing a contents scramble system (hereinafter abbreviated as CSS) in acertain area, which is an information area related to copyrightprotection such as the CSS system. A system protecting illegal copyingis employed such that an information related to the copyright protectionsuch as the CSS system is read out by a DVD-Video disc reproducingapparatus, and then the reproducing apparatus reproduces contents of theDVD-Video disc by using the information related to the copyrightprotection.

In a case that a recordable optical disc, which is recorded withcontents of a DVD-Video disc in conjunction with an information relatedto copyright protection by a recording apparatus for a high densitydisc, is reproduced by a DVD-Video disc reproducing apparatus, thereexisted a problem such that the information related to copyrightprotection can be read out and the contents of the DVD-Video disc beingprohibited to copy can be reproduced. Accordingly, copyright protectionof a DVD-Video disc, which is prohibited to copy, can not be fullyprotected.

SUMMARY OF THE INVENTION

Accordingly, in consideration of the above-mentioned problems of theprior art, an object of the present invention is to provide aninformation recording medium such as a DVD-RW disc, which can berecorded and reproduced, and a recording method and a reproducing methodthereof.

In order to achieve the above object, the present invention provides,according to a first aspect thereof, an information recording mediumcomprising: an information track formed spirally or in coaxial circles;a recordable area for information being prerecorded with a frequencysignal and an address signal from an inner circumference of theinformation track; and a read only area being recorded with areproduction signal as a readable pit, wherein there existed a boundarybetween the recordable area and the read only area.

According to a second aspect of the present invention, there provided aninformation recording medium comprising: an information track formedspirally or in coaxial circles; a first read only area recorded with afrequency signal being recorded as a pit being able to read out areproduction signal; and a second read only area recorded as a pit beingunable to read out a reproduction signal and prerecorded with afrequency signal and an address signal, wherein there existed a boundarybetween the first read only area and the second read only area.

According to a third aspect of the present invention, there provided aninformation recording medium comprising: an information track formedspirally or in coaxial circles; a recordable area for information beingprerecorded with a frequency signal and an address signal from an innercircumference of the information track; a first read only area recordedwith a frequency signal being recorded as a pit being able to read out areproduction signal; and a second read only area recorded as a pit beingunable to read out a reproduction signal and prerecorded with afrequency signal and an address signal, wherein there existed a boundarybetween the recordable area and the first read only area and anotherboundary between the first read only area and the second read only area.

According to a fourth aspect of the present invention, there provided arecording method of the above-mentioned information recording medium,the recording method comprising steps of: identifying the informationrecording medium by reproducing an identification information out ofinformation recorded on the information recording medium; judging theboundary being identified in the step of identifying by using an addressinformation; and recording in a vicinity of the boundary for performinga recording process by altering a control method of tracking.

According to a fifth aspect of the present invention, there provided areproducing method of the above-mentioned information recording medium,the reproducing method comprising steps of: identifying the informationrecording medium by reproducing an identification information out ofinformation recorded on the information recording medium; judging theboundary being identified in the step of identifying by using an addressinformation; and reproducing the boundary for performing a reproducingprocess by altering a control method of reproducing.

Other object and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a partially enlarged cross sectional view of a resistboard of an information recording medium according to a first embodimentof the present invention.

FIG. 1( b) is a partially enlarged plan view of the resist board shownin FIG. 1( a).

FIG. 2( a) shows configuration of a data sector, which constitutes arecording information to be recorded on an information recording mediumof the present invention.

FIG. 2( b) shows an ECC block being composed of the data sector shown inFIG. 2( a)

FIGS. 3( a) to 3(d) are exemplary drawings for explaining that an ECCblocked data is recorded sector by sector in a specific area of aninformation recording medium of the present invention.

FIG. 4 shows a physical format of one sector in a DVD-RW (DigitalVersatile Disc for Re-recordable) disc, which is one embodiment of aninformation recording medium according to the present invention.

FIG. 5 shows a configuration of a lead-in area and a data area of aninformation recording medium of the present invention.

FIG. 6( a) is a partially enlarged cross sectional view of a resistboard of an information recording medium according to a secondembodiment of the present invention.

FIG. 6( b) is a partially enlarged plan view of the resist board shownin FIG. 6( a).

FIG. 7( a) is a comparative example of a partially enlarged crosssectional view of a resist board of an information recording medium in acutting state.

FIG. 7( b) is a partially enlarged plan view of the resist board shownin FIG. 7( a).

FIG. 8( a) is another comparative example of a partially enlarged crosssectional view of a resist board of an information recording medium in acutting state.

FIG. 8( b) is a partially enlarged plan view of the resist board shownin FIG. 8( a).

FIG. 9( a) is a track configuration of a type one disc showingallocation of recording and reproducing operation according to thepresent invention.

FIG. 9( b) is a track configuration of a type two disc showingallocation of recording and reproducing operation according to thepresent invention.

FIG. 10 shows a configuration of a lead-in area and a data area of aninformation recording medium according to a third embodiment of thepresent invention.

FIG. 11( a) shows a configuration of a lead-in area and a data area ofan information recording medium according to a fourth embodiment of thepresent invention.

FIG. 11( b) is a comparison table showing differences between a type 4and a type 5 shown in FIG. 11( a).

FIG. 12( a) shows a configuration of a lead-in area and a data area ofan information recording medium according to a fifth embodiment of thepresent invention.

FIGS. 12( b) through 12(d) are comparison tables showing differencesbetween a type 6 and a type 7 shown in FIG. 12( a).

FIG. 13( a) is a partially enlarged cross sectional view of a resistboard of an information recording medium according to a sixth embodimentof the present invention in a cutting state.

FIG. 13( b) is a partially enlarged plan view of the resist board shownin FIG. 13( a).

FIG. 14( a) shows a configuration of a lead-in area and a data area ofan information recording medium according to the sixth embodiment of thepresent invention.

FIGS. 14( b) and 14(c) are comparison tables showing differences betweena type 6 and a type 8 shown in FIG. 14( a).

FIG. 15 is a waveform of a tracking error signal according to a seventhembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior to depict each embodiment of the present invention, configurationand recording method of a recordable disc such as a DVD-RW (DigitalVersatile Disc for Re-recordable) is described first in general.

In a recordable disc such as a DVD-RW disc, an information related to acopyright protection information is recorded in a specific area (aninformation area for copyright) of the DVD-RW disc by an emboss pre-pit,wherein the specific area is usually recorded with a copyrightprotection information of a DVD video in a normal state and is treatedso as not to be able to overwrite the recorded copyright protectioninformation. By his method, in a case that a DVD video contents, whichis not comply with the copyright protection information, is recorded ona DVD-RW disc by using a high density disc recording apparatus, and thenthe DVD video contents is reproduced by a DVD video reproducingapparatus, the copyright protection information corresponding to thecontents can not be reproduced, so that the DVD video contents can notbe reproduced. Accordingly, copyright of a DVD video, which isprohibited from copying, can be protected.

A recordable optical disc is prerecorded with various information suchthat a prerecorded information such as a condition of specifyingluminous energy of a laser beam for recording, a disc type, and a nameof manufacturer, or an address information for being able to find out aspecific position of a recordable guide groove and further, a frequencyinformation utilized for controlling a number of rotations of the discare prerecorded in a specific position respectively.

Such a recordable optical disc is designed to be used immediately afterthe disc is purchased. As described in following paragraphs (1) through(3), it is caused by being recorded with the prerecorded information orthe address information in a specific position as mentioned above.

The above-mentioned prerecorded information is recorded as an emboss pitwhen cutting a master disc. By forming a disc substrate by using a metalmother mold, which is produced by the master disc, the prerecordedinformation is recorded in a specific position of the disc substrate ofthe above-mentioned recordable optical disc such as a lead-in area ofthe disc. Further, in a case that the above-mentioned prerecordedinformation is not recorded while cutting a master disc, the informationis additionally recorded in the above-mentioned specific position as apit or a mark by using a recording device for recording the prerecordedinformation.

On the other hand, the above-mentioned address information is recordedas an LPP (Land Pre-Pit) in a specific position of a guide groove ofwhich width is widened.

Further, the above-mentioned frequency information is recorded as awobble frequency, which is a frequency of wobbling a guide groovemicroscopically in a radial direction.

Recording the above-mentioned prerecorded information, addressinformation, frequency information, and a guide groove in a specificposition of a disc substrate is actually performed as follows: coatingphotosensitive resist uniformly on a glass substrate, which is polishedflat, in a thickness of corresponding to a depth of guide groove. In acase that a recordable optical disc is a DVD-RW disc, the photosensitiveresist is coated uniformly on the glass substrate as thick asapproximately 30 nm.

The glass substrate uniformly coated with photosensitive resist(hereinafter referred to resist board) is transferred to a cuttingapparatus. The cutting apparatus is equipped with a laser beam controldevice, which makes a laser beam for cutting irradiated from a lightsource intermitted or wobbled microscopically right and left in a radialdirection. By irradiating the laser beam for cutting, which is anintermittent light beam or wobbled microscopically in the radialdirection, on the resist board, the above-mentioned prerecordedinformation and address information and frequency information arerecorded in an specific position respectively after the resist board ismounted on a predetermined position in the cutting apparatus.

Two laser beams for cutting are utilized herein, one of them is utilizedfor forming a guide groove in a continuous light beam and the other isutilized for forming an LLP in an intermittent light beam. Further, theprerecorded information mentioned above is recorded as a pit in apredetermined position such as a lead-in area by intermitting the laserbeam for cutting utilized for forming a guide groove.

The resist board is developed after cutting the resist board, and then ashape information, which is the aforementioned prerecorded informationand address information and frequency information and guide groove, isdeposited as shape change on the resist board. The developed resistboard is covered with a conductive thin film. By using an electroplatingmethod, the shape information on the resist board is transcribed on aplated board. The plated board is formed in predetermined dimensions andbecomes a metal mother mold. By using an injection-molding machineinstalled with the metal mother mold, the shape information istranscribed on a plastic substrate as shape change. Accordingly, a discsubstrate for a recordable optical disc is obtained.

The specific position on the disc substrate at where the shape change istranscribed is called an information surface. A functional film forrecording is formed on the information surface and finally a recordableoptical disc is manufactured through various after-processes. The discsubstrate produced through an injection-molding process by using themetal mother mold mentioned above has guide grooves and pits in a samedepth throughout the disc substrate.

As mentioned above, since a guide groove of a recordable optical disc isformed in a necessary depth for tracking guide while recording, when asignal from a recorded recording mark is maximally read out whilereproducing, a problem such that reflectivity decreases due to a phasedifference of reflected light caused by a depth difference between aland of a recording groove and the guide groove arises. In a case of theland groove recording method utilized for a repeatedly rewritableDVD-RAM (DVD-Random Access Memory) disc, a guide groove is formed asdeep as possible so as to decrease an inter-track cross-talk between aland allocated between guide grooves and a groove or a guide groove.However, a depth of a guide groove is usually formed shallower than adepth from which a guide signal can most effectively be read out, thatis, approximately one eighth of a reproduction wavelength of laser beam.Further, a tracking operation for a guide groove is performed by thepush-pull method.

On the other hand, in a case of a read only disc such as a DVD-ROM(DVD-Read Only Memory) disc, a pit depth is designated to be a certaindepth at where diffraction by a laser beam is effectively performed,that is, approximately one quarter of a reproduction wavelength of thelaser beam so as to obtain a reproduction signal as large as possible.Therefore, a signal necessary for tracking can not be sufficientlyobtained by the push-pull method applied to a pit array, so that atracking operation is performed by the phase difference method.

As mentioned above, in a case of a DVD-RAM disc as a recordable opticaldisc, a depth of a guide groove is designated so as to perform recordingand reproducing operation effectively. In a case of a DVD-ROM disc as aread only disc, a depth of a pit is designated so as to be convenientfor reproducing.

COMPARATIVE EXAMPLE

Following two methods (1) and (2) are considered to provide a guidegroove and a pit of which depth is different from each other in one discsubstrate of a recordable optical disc.

FIGS. 7( a) and 7(b) are a comparative example of a partially enlargedcross sectional view and a plan view of a resist board of an informationrecording medium of the present invention respectively in a cuttingstate.

FIGS. 8( a) and 8(b) are another comparative example of a partiallyenlarged cross sectional view and a plan view of a resist board of aninformation recording medium of the present invention respectively in acutting state.

In FIGS. 7( a) and 8(a), reference signs “A” and “B” are a laser beam“A” for cutting utilized for forming a pit and a guide groove and alaser beam “B” for cutting utilized for forming a land pre-pit (LPP)respectively.

In FIGS. 7( b) and 8(b) and in a following explanation, a symbol “LPP”shows a land pre-pit, which is formed on a land.

A first cutting method is such that as shown in FIGS. 7( a) and 7(b), bychanging an output of a laser beam for cutting (hereinafter referred tolaser beam “A”) utilized for forming pits P11 and P12 and guide groovesG11 and G12 while cutting a resist board 110, a depth convenient forreproducing a pit is formed by a certain output of the laser beam “A”and a shallower guide groove convenient for recording the guide grooveis formed by another output of the laser beam “A”. However, according tothe first cutting method, a bottom of the shallower guide groove doesnot reach a top surface of a glass substrate 101 allocated under aresist layer, so that a bottom surface of the guide groove is determinedby output distribution of the laser beam “A” not by the glass substrate101. Therefore, a shape of a bottom of guide groove becomes a funnelshape not flat. Actual output distribution of the laser beam “A” isuneven as maximum at a center of the laser beam, so that uniformity of abottom surface of a guide groove is hardly realized. Accordingly, asignal characteristic of recording and reproducing is severelydeteriorated.

With respect to a second cutting method, as shown in FIGS. 8( a) and8(b), both the laser beam “A” for forming pits P21 and P22 and guidegrooves G21 and G22 and the laser beam “B” for forming a land pre-pitare utilized while cutting a resist board 120. By using the laser beam“A” in a constant output, the pits P21 and P22 and guide grooves G21 andG22 are formed in a same depth respectively, wherein each bottom of thepits P21 and P22 reaches the top surface of the glass substrate 101allocated under a resist layer. Further, the second cutting method issuch that a resist adjacent to both edges of a guide groove is exposedas high as desired by using the laser beam “B” and a relative depthamong guide grooves are adjusted. By using the second cutting method,each bottom of the guide grooves G21 and G22 is the top surface of theglass substrate 101, so that a bottom shape of the guide grooves G21 andG22 becomes flat. Accordingly, a similar recording and reproducingcharacteristic to a current disc formed only with guide grooves can beobtained.

However, while reproducing a boundary at where a pit array changes overto a guide groove and vise versa, the second cutting method generatesdisorder such that a pit signal and a LPP signal at a position ofchanging from a pit array and another pit array over to a guide grooveand vise versa is deficient, an amplitude difference between the pitsignal and the land pre-pit signal occurs, a tracking signal amplitudevaries by a method such as the push-pull method, and offset occursbecause a height of a resist allocated between two pit arrays isdifferent from that of another resist allocated between a pit array anda guide groove or between a guide groove and a pit array.

As mentioned above, in a case that a pit array having a depth ofconvenient for reproducing exists together with a guide groove having adepth of convenient for recording and reproducing in one recordableoptical disc, it is desirable to design a guide groove of which bottomreaches a top surface of a glass substrate and becomes flat in order tofully ensure a recording and reproducing characteristic of the guidegroove. Further, while reproducing a transitional area from a pit arrayto a guide groove and/or from a guide groove to a pit array, it is foundthat there is existed a recording apparatus, which is deficient in a pitsignal and disordered in reproduction tracking by the push-pull methodat the transitional area. This is caused by that the recording apparatuscan not correctly read out a signal of pit array, which is affected byadjustment of resist thickness of an adjacent guide groove in atransitional area from a guide groove to a pit array. Therefore, the pitarray and the guide groove are deficient in total signal information ofadjacent pit arrays. In such a recording apparatus of being disorderedin tracking, a tracking control signal shows an abnormal value at atransitional area from a pit array to a guide groove and/or from a guidegroove to a pit array and tracking becomes out of order. Accordingly, aposition of reproducing track skips more than some ten tracks andrecording and reproducing of a desired position can not be performed.

Accordingly, in order to obtain a sufficient reproduction signal byrecording in a guide groove and reproducing from the guide groove and inorder to record an information disabled to rewrite in a pit array, it isnecessary for a depth of a guide groove and a pit array to be an optimumdepth respectively. Further, both bottoms of a guide groove and a pitare allocated at a top surface of a glass substrate and are flat. A discas one recordable optical disc is required, wherein a pit array and aguide groove of the disc are excellent in a recording and reproducingcharacteristic, further, the disc can comply with recording andreproducing even though a pit signal drops out at a transitional areafrom a pit to a guide groove, and wherein a tracking signal is notdisturbed by any tracking method.

With returning back to common description to each embodiment, a dataconfiguration and a format will be depicted.

According to an aspect of the present invention, there provided aninformation recording medium, which can stably reproduce a copyrightprotection information of a read only pit array and can record contentsin accordance with the copyright protection information. Particularly,positions of bottoms of a guide groove and a pit array formed on a discsubstrate are in a same flat surface and bottom shapes of them are flat.Further, there provided an intermediate area being composed of a pitarray of which height changes between a height from a bottom surface toa sidewall of a guide groove and another height from the bottom surfaceto a sidewall of the pit array. By reproducing the intermediate areawith a tracking method of either the differential push-pull system orthe phase differential system, an excellent reproduction information canbe obtained from a read only pit array and a record only guide grooverespectively. Furthermore, an optimum tracking characteristic can alwaysbe obtained in an area not recorded as well as in a recorded area.

FIG. 2( a) shows configuration of a data sector, which constitutes arecording information to be recorded on an information recording mediumof the present invention.

FIG. 2( b) shows an ECC block being composed of the data sector shown inFIG. 2( a)

FIGS. 3( a) to 3(d) are exemplary drawings for explaining that an ECCblocked data is recorded sector by sector in a specific area of aninformation recording medium of the present invention.

FIG. 4 shows a physical format of one sector in a DVD-RW disc, which isone embodiment of an information recording medium according to thepresent invention.

By using a DVD-RW disc as an embodiment of an information recordingmedium of the present invention, recording an information on the DVD-RWdisc is mainly explained in a following description. However, thepresent invention can apply to other recordable disc such as a CD-RW(Compact Disc-ReWritable) disc and a DVD+RW disc, and a high densityoptical disc such as a DVD disc in a next generation.

First of all, with referring to FIGS. 2( a) through 4, a physical formatin general and an error correction process of a recording information ora lead-in information is depicted when the recording information isrecorded on a DVD-RW disc.

With referring to FIGS. 2( a) and 2(b), an error correction code (ECC)block as an error correction unit in an error correction process of aDVD-RW disc of the present invention is explained.

Generally, a recording information to be recorded on a DVD-RW disc isconstituted by a physical configuration being composed of a plurality ofdata sectors 20 shown in FIG. 2( a). 2064 bytes of one data sector 20comprises 4 bytes of an ID information 21 indicating a start position ofthe data sector 20, 2 bytes of an ID information error correction code(IED) 22 for correcting an error of the ID information 21, 6 bytes of aspare data (such as CMP) 23, 2048 bytes of a data area 24 for storing amain data to be recorded, and 4 bytes of an error detection code (EDC)25 for detecting an error in the data area 24 in order from a head ofthe data sector. A sequence of a plurality of data sectors 20 configuresa recording information to be recorded.

With referring to FIG. 2( b), a process of configuring an ECC block byusing the data sector 20 is depicted next. As shown in FIG. 2( b), onedata sector 20 composed of 2064 bytes is divided into 12 blocks 33-1through 33-12, which are composed of 172 bytes respectively. Eachdivided block (hereinafter generically referred to a data block 33) isallocated in a vertical direction, wherein 12 lines of the data block 33are allocated in the vertical direction.

Adding a 10-byte ECC parity in (PI) code 31 to an end of each data block33 configures one correction block 34. In this stage, 12 lines ofcorrection block 34 added with the PI code 31 are allocated in thevertical direction. After that, the process is applied to 16 datasectors 20 repeatedly. Accordingly, 192 lines of correction blocks 34-1through 34-192 are obtained.

While 192 correction blocks 34-1 through 34-192 (hereinafter genericallyreferred to correction blocks 34) are drawn up in 192 lines vertically,the 192 correction blocks 34 are divided into one byte each from an eachhead of correction blocks 34 in the vertical direction. In other words,each line of correction blocks 34 is divided into 182 data horizontally.Then, 16 ECC parity out (PO) codes 32 are added to each data of dividedcorrection blocks 34, wherein the PO code 32 is also added to dataincluded in the PI code 31.

By the above-mentioned process, one ECC block 30 including 16 datasectors 20 each of which is composed of 12 lines of data blocks 33 isconfigured as shown in FIG. 2( b). In this case, a total amount ofinformation included in one ECC block 30 is: (172+10) bytes×(192+16)lines=37856 bytes. Further, an actual amount of data, which are recordedin the data area 24 of one data sector 20, is: 2048 bytes×16=32768bytes.

Furthermore, one byte of data is indicated as “D#.*” in the ECC block 30shown in FIG. 2( b). The “D1.0”, for example, indicates one byte ofdata, which is allocated in the first line and in the zeroth column. Ina case of “D190.170”, it is one byte of data allocated in the 190th lineand in the 170th column. Moreover, the PI code 32 is allocated in the172nd through 181st columns, and the PO code 32 is allocated in the192nd through 207th lines.

In addition thereto, one correction block 34 is continuously recorded ona DVD-RW disc. As shown in FIG. 2( b), in order to correct a data drawnup in the horizontal direction by the PI code 31 and to correct a datadrawn up in the vertical direction by the PO code 32, the ECC block 30is configured to include both the PI code 31 and the PO code 32. Inother words, in the ECC block 30 shown in FIG. 2( b), it is possible tocorrect error doubly in the horizontal direction and the verticaldirection. Accordingly, a stronger error correction than the errorcorrection process utilized for a conventional CD disc can be ensured.

An actual error correction is depicted next. In a case that onecorrection block 34, which is composed of a data of 182 bytes in totalincluding one line of PI code 31 as mentioned above and is recorded on aDVD-RW disc continuously, is up to 5 bytes, for example, an error can becorrected even though a part of the data is destroyed by a scratch or acut. However, in a case that one correction block 34 is more than 6bytes and all the one line of data is destroyed by a scratch on a DVD-RWdisc, the PI code 31 can not correct the data any more. Although all theone line of data is destroyed, it is only one byte of a destroyed datafor one column of the PO code 32 with viewing from a vertical direction.Accordingly, by correcting an error by using each line of the PO code32, the error can be properly corrected and a data can be accuratelyreproduced even though one correction block 34 is totally destroyed.However, a scratch must be minimized because the scratch may cause anerror of a next horizontal line in a vertical direction if the scratchof a horizontal line is enlarged as far as considering an acquiredscratch. In this connection, an error in a vertical direction can becorrected even though a data in 8 vertical columns is destroyed.Further, errors in 16 vertical columns can also be corrected by theeraser correction method.

With referring to FIGS. 3( a) through 3(d), they depict how the datasector 20, which is configured to be the ECC block 30 shown in FIG. 2(b), is actually recorded on a DVD-RW disc. In FIGS. 3( a) through 3(d),a data indicated as “D#.*” is corresponding to a data indicated in FIG.2( b).

When recording the ECC block 30 on a DVD-RW disc, as shown in FIGS. 3(a) and 3(b), the ECC block 30 is divided into 16 recording sectors 40-1through 40-16 (hereinafter generically referred to recording sector 40)by being drawn up per each correction block 34 in one line horizontallyand by being interleaved. In this case, one recording sector 40 iscomposed of 2366 bytes (37856 bytes÷16) of information. In the recordingsector 40, there existed the data sector 20, the PI code 31, and the POcode 32 mixed. However, the ID information 21 shown in FIG. 2( a) isallocated at a head of each recording sector 40.

One recording sector 40 is divided into 91 bytes each of a data 41, anda sync “H” is added to each data 41 as shown in FIG. 3( c). Therecording sector 40 is modulated by the eight to sixteen (8/16)modulation method, and then the recording sector 40 is divided into 26sync frames 42-1 through 42-26 (hereinafter generically referred to syncframe 42) and one sync frame 42 is formed per each data 41 as shown inFIG. 3( d). In other words, one recording sector is composed of 26 syncH′ and 26 data 43-1 through 43-26 (hereinafter generically referred todata 43) and each sync frame 42 is composed of a sync H′ and a data 43.Further, an information amount of one sync frame 42 is: 91bytes×8×(16÷8)=1456 bytes. An information is recorded on a DVD-RW discby a series of the sync frame 42.

With referring to FIG. 4, the above-mentioned configuration issummarized. A head sector of one ECC block 30 being composed of 16sectors is configured as a physical format as shown in FIG. 4. In otherwords, one horizontal line is composed of 172 bytes of data, 10 bytes ofthe PI code 31, and 4 bytes of sync, and is configured 186 bytes intotal. Further, the head sector is composed of 12 lines and one line ofPO code 32, and configured 13 lines in total. The sync is composed of 2bytes each of H0 through H25, that is, 26 in total.

By recording an information on a DVD-RW disc with configuring thephysical format as mentioned above, an amount of data blocks beingdestroyed can be minimized by performing the 8/16 demodulation andde-interleave when reproducing the information, and the original ECCblock 30 can be restored thereby. Accordingly, the information can mostaccurately be reproduced by performing a powerful error correction asmentioned above. An information relating to copyright protection such asa media key block, which is allocated in a lead-in information area, isrecorded as a part of data of such the ECC block.

First Embodiment

According to a first embodiment of the present invention, there isprovided a recordable optical disc as an information recording medium.The recordable optical disc is designed such that a groove depth of aguide groove and a pit depth of a pit array is different from each otherby exposing resist of a guide groove, and that bottoms of a guide grooveand a pit array are formed by a top surface of a glass substrate.Further, in a transitional area from a pit array to a guide groove orvise versa, an intermediate area, wherein a height of a guide groove ischanged, is provided by changing an output of a laser beam for exposingresist. A tracking error signal in an allowable amplitude difference anda signal within a range of offset level can be obtained by thedifferential push-pull method and the differential phase detect (DPD)method in the intermediate area.

By the above-mentioned method, it is confirmed that a pit signal of apit array adjacent to a guide groove in a transitional area from the pitarray to the guide groove or vise versa is not severely affected byresist exposure for adjusting a resist thickness of the guide groove.Further, dropout or damage of a pit shape does not occur, so that a pitrecording information can be accurately read out and a recordinginformation can be accurately recorded in a recording area.

FIG. 1( a) is a partially enlarged cross sectional view of a resistboard of an information recording medium according to a first embodimentof the present invention.

FIG. 1( b) is a partially enlarged plan view of the resist board shownin FIG. 1( a).

An information recording medium according to the first embodiment of thepresent invention is a recordable optical disc having a disc substrateformed with a resist board 100 shown in FIGS. 1( a) and 1(b). In FIG. 1(a), the recordable optical disc is composed of read only areas P1 andP2, a recording/reproducing area A1 formed with guide grooves 1 athrough 1 c (hereinafter generically referred to guide groove “1”) andan intermediate area, which is formed between the areas P1 and P2.Further, as shown in FIG. 1( b), other guide grooves 2 a through 2 d(hereinafter generically referred to guide groove “2”) are allocated inthe area P2. Furthermore, a guide groove “3” is allocated in theintermediate area.

As shown in FIGS. 1( a) and 1(b), all bottoms of pit arrays PAa throughPAc (hereinafter generically referred to pit array PA) in the area P1,pit arrays PBa through PBd (hereinafter referred to pit array PB) in thearea P2, and a pit array PM in the intermediate area are in a same flatlevel, wherein each bottom of pit arrays PA, PB, and PM is allocated ona top surface of a glass substrate 101.

A pit depth, that is, an optical pit depth of the pit array PM to abottom of the pit array PM in the intermediate area is constituted so asto decrease, for example, from an optical depth “a” of a land L101 to anoptical depth “b” of a land L102 as shown in FIGS. 1( a) and 1(b).

As mentioned above, in a recordable optical disc from which areproduction signal can be obtained sufficiently by recording in andreproducing from a guide groove and further, on which a not rewritableinformation can be recorded by a pit array, a groove depth of guidegroove and a pit depth of a pit array is necessary to be a most suitabledepth respectively. Furthermore, both bottoms of a guide groove and apit are positioned on a top surface of the glass substrate 101.Moreover, the recordable optical disc must be excellent in a recordingand reproducing characteristic. In addition thereto, the recordableoptical disc must be a disc such that a pit signal does not drop out ora tracking signal is not disturbed in a transitional area from a pit toa guide groove or vise versa.

Referring back to FIGS. 1( a) and 1(b), a master disc of a recordableoptical disc according to the first embodiment is produced by a cuttingdevice (not shown) in accordance with following processes.

Resist is coated over the glass substrate 101 of which surface is finelyground as thick as a most deep shape corresponding to a pit depth of apit array. Two laser beams “A” and “B” are irradiated from a laser beamsource (not shown). A light polarizing device (not shown) for shifting alaser beam to right and left slightly in a horizontal direction and alight modulator (not shown) for changing laser beam strength is providedin a light path of the laser beam “A”.

As shown in FIG. 1( a), on the resist board 100, a guide groove “1” ofwhich bottom is allocated on the top surface of the glass substrate 101is recorded by the laser beam “A” in a laser beam strength PA1 suitablefor recording a guide groove “1”, wherein the bottom of the guide groove“1” is exposed as deep as the top surface of the glass substrate 101.The guide groove “1” is slightly wobbled by a predetermined frequency.On the other hand, the laser beam “B” records in a laser beam strengthPB1 so as to remain a necessary thickness of resist for forming theguide groove “1”. Because there is existed thicker resist than necessarythickness for forming a guide groove having a proper groove depth in aland, which is allocated between the guide grooves “1”. Further, thelight modulator (not shown) outputs certain laser beam strengthnecessary to form a land pre-pit (LPP) when recording the LPP.

As shown in FIG. 1( a), the other guide groove “2”, which is provided ina pit area composed of the pit array PB in the area P2, is exposed bythe laser beam “A” being suitable for recording such a guide groove “2”after the guide groove “1” in the area A1 is formed, wherein a bottom ofthe guide groove “2” is desired to be exposed as deep as the top surfaceof the glass substrate 101. However, the depth is not limited to thedesired depth. A specific thickness of resist necessary for the pitarray PB in the area P2 is formed on a land between the pit arrays PB byusing the laser beam “B” in a laser beam strength PB3 so as to remain aresist thickness equivalent to that of the guide groove “1” in the areaA1 and so as to increase a resist thickness gradually, Further, in theguide groove “1” adjacent to the pit array PB in the area P2, a certainthickness of resist equivalent to that of the pit array PB in the areaP2 is formed by the laser beam “B” in a laser beam strength PB1.Furthermore, the laser beam “B” outputs a laser beam in certain strengthnecessary for forming a LPP when recording the LPP. In this case, thelaser beam “B” can be slightly wobbled by a predetermined frequency.

Such an identification information for identifying a recordable opticaldisc is recorded in the area P1 having the pit array PA by using thelaser beam “A” in a laser beam strength PA2 being suitable for recordinga pit and for exposing all resist in a depth direction. Further, thearea P1 is exposed as deep as the top surface of the glass substrate101. In this case, the pit array PA is slightly wobbled by apredetermined frequency. However, in some cases, wobbling is notnecessary.

As mentioned above, the recording/reproducing area (area A1), the readonly area (areas P1 and P2), and the intermediate area is formed.Accordingly, the guide groove “1”, pit arrays PA and PB, and the LPP isrecorded on one resist board 100 as a latent image.

In a succeeding developing process, the latent image is deposited as ashape change and transferred to a metal master disc producing process.In the metal master disc producing process, the resist board 100 iscovered with a conductive film such as nickel and formed with a nickelfilm thereon by nickel plating. A metal master disc formed with nickelis peeled off from the resist board 100. The peeled off metal masterdisc is cleaned and processed in predetermined dimensions so as to beinstalled on an injection mold. The metal master disc processed iscalled a mother die. The mother die is installed on the injection moldand a plastic disc substrate is formed by an injection molding method.

A functional film for recording or a recording layer is filmed on thedisc substrate. A protective film, for example, is coated thereon oranother substrate called a dummy substrate is stuck on the discsubstrate. Accordingly, a recordable disc can be produced.

As shown in FIGS. 1( a) and 1(b), the intermediate area having the pitarray PM is formed between the area P1 having the pit array PA and thearea P2 having the pit array PB. An optical depth of the pit array PM inthe intermediate area is a same optical depth as that of the area P1 oris shallower than that of the area P1 slightly. In some cases, anoptical depth can not be regulated accurately.

A formatting method of a disc is depicted next.

FIG. 5 shows configuration of a lead-in area and a data area of aninformation recording medium of the present invention.

In FIG. 5, a “type 1” represents a type of a disc such as shown in FIGS.8( a) and 8(b), wherein an area changes continuously from a track of aread only pit area in a right side of the disc to a recordable groovearea in a left side of the disc. On the other hand, a “type 2”represents another type of a disc such as shown in FIGS. 1( a) and 1(b),wherein there is existed an area having a pit as an intermediate area ofwhich depth changes between a track provided in a read only pit area ina right side of the disc and a recordable groove area in a left side ofthe disc.

FIG. 5 exhibits a structure of a disc according to the present inventionover a lead-in area allocated in an innermost circumference area througha data area allocated in an outer most circumference area. Amanufacturing process varies in these areas as mentioned above. Thestructure is constituted as a format so as to be able to exist two typesof discs, “type 1” and “type 2”, together. The format is not so well ina signal performance or a recording and reproducing characteristic for atype 1 disc. However, the type 1 disc can rather easily be manufactured.On the other hand, with respect to a type 2 disc, the format isdesirable for a signal performance or a recording and reproducingcharacteristic. Further, a manufacturing method can be more flexible bybeing existed two methods, which restrict a signal performance in anintermediate area, together.

A lead-in area of a type 1 disc is divided into four regions from aninner circumference area to an outer circumference area in order. Thefour regions are as follows:

A first region covering from an inner circumference area as an area ofenabling to record and reproduce over to another area of enabling torecord and reproduce having a LPP, which includes an information such asan address in a land area allocated side of a wobbled groove area havinga depth of approximately λ/12 in an outer circumference direction, andan tracking error signal of the differential push-pull method can beobtained therein, such as an “initial zone”, a “system reserved zone”, a“buffer zone 0 (zero)” being composed of totally “00h”, a “RW-physicalformat information zone”, a “reference code zone”, a “buffer zone 1”,and a “linking loss area”.

A second region is a “control data zone” or a “readable emboss zonewithout LPP” area, which is a read only area of enabling to read out arecording signal and enabling to obtain a DPD (differential phasedetect) tracking error signal composed of a pre-pit without a LPP, andfurther, includes an information related to copyright protection and alead-in information, wherein the region is constituted by a depth ofapproximately λ/4 and wobbled.

A third region is an “unreadable emboss zone with LPP” area, which is aread only area of being not able to read out a recording/reproducingsignal although being able to obtain a DPD tracking error signalcomposed of a pre-pit with a LPP, wherein the zone is constituted by adepth of approximately λ/12 and wobbled.

A fourth region is composed of a “buffer zone 2”, which is an area ofenabling to record and reproduce having a LPP including an informationsuch as an address in a land area allocated side of a groove area in anouter circumference direction with wobbled, wherein an tracking errorsignal of the differential push-pull method can be obtained, and a “dataarea” for recording user's contents succeeding thereafter.

In FIG. 5, an alphanumeric letters indicated at the right upper cornerof each zone is a start address of each zone. An operation of a type 1disc while recording is shown as “Write Mode” and an operation whilereproducing is shown as “Read Mode” in the left side of FIG. 5respectively. Wordings such as “recording”, “reading”, and “seek”represent a recording operation, a reproducing operation, and a seekingoperation or a skipping a track operation respectively. Further, awording “read gen wclk” represents an operation of producing a recordingclock signal and a recording timing signal by reproducing a wobblesignal and a LPP address signal.

A lead-in area of a type 2 disc is divided into six regions from aninner circumference area to an outer circumference area in order. Thesix regions are as follows:

(2-1) A first region covering from an inner circumference area as anarea of enabling to record and reproduce over to another area ofenabling to record and reproduce having a LPP, which includes aninformation such as an address in a land area allocated side of awobbled groove area having a depth of approximately λ/12 in an outercircumference direction, and an tracking error signal by thedifferential push-pull method can be obtained therein, such as the“initial zone”, the “system reserved zone”, the “buffer zone 0 (zero)”being composed of totally “00h”, the “RW-physical format informationzone”, and the “reference code zone”.

(2-2) A second region is composed of a “boundary flag zone 1”, which isan arbitrary zone to be provided, recorded with a code of judging a discwhether the disc is a type 1 or a type 2 and a “boundary emboss zone 1”as the aforementioned intermediate area, wherein the “boundary embosszone 1” is a pit area formed with a depth from λ/12 to λ/4 approximatelyand wobbled. Further a tracking error signal by the differentialpush-pull method and a DPD tracking error signal can be obtainedtherefrom, wherein a “boundary flag 1” is written in a LPP or the“control data zone”.

(2-3) A third region is the “control data zone” or the “readable embosszone without LPP” area, which is a read only area of enabling to readout a recording signal and enabling to obtain a DPD tracking errorsignal composed of a pre-pit without a LPP, and further, includes aninformation related to copyright protection and a lead-in information,wherein the region is constituted by a depth of approximately λ/4 andwobbled.

(2-4) A fourth region is composed of a “boundary flag zone 2”, which isan arbitrary zone to be provided, recorded with a code of judging a discwhether the disc is a type 1 or a type 2 and a “boundary emboss zone 2”constituted in reverse to the aforementioned intermediate area, whereinthe “boundary emboss zone 2” is a pit area formed with a depth from λ/4to λ/12 approximately and recorded with wobbling and a LPP. Further, atracking error signal by the differential push-pull method and a DPDtracking error signal can be obtained therefrom, wherein the LPP isarbitrarily to be recorded, and wherein a “boundary flag 2” is writtenin the “control data zone”.

(2-5) A fifth region is the “unreadable emboss zone with LPP” area,which is a read only area of being not able to read out arecording/reproducing signal although being able to obtain a DPDtracking error signal composed of a pre-pit with a LPP, wherein the zoneis constituted by a depth of approximately λ/12 and wobbled.

(2-6) A sixth region is composed of the “buffer zone 2”, which is anarea of enabling to record and reproduce having a LPP including aninformation such as an address in a land area allocated side of a groovearea in an outer circumference direction with wobbled and a depth ofapproximately λ/12, wherein an tracking error signal by the push-pullmethod can be obtained, and the “data area” for recording user'scontents.

In FIG. 5, an alphanumeric letters indicated at the right upper cornerof each zone is a start address of each zone. An operation of a type 2disc while recording is shown as “Write Mode” and an operation whilereproducing is shown as “Read Mode” in the right side of FIG. 5respectively. Wordings such as “recording”, “reading”, and “seek”represent a recording operation, a reproducing operation, and a seekingoperation or a skipping a track operation respectively. Further, awording “read gen wclk” represents an operation of producing a recordingclock signal and a recording timing signal by reproducing a wobblesignal and a LPP address signal.

Both the “boundary flag zone 1” and the “boundary flag zone 2” are notnecessary to be allocated in the specific regions as shown in FIG. 5.However, they must be prerecorded with embedding in the “control datazone” having a lead-in information in conjunction with an addressinformation of a LPP in a recordable area so as to change a method ofrecording/reproducing in accordance with a type of disc, type 1 or type2, and so as to be able to judge whether a disc to be recorded andreproduced is the type 1 or type 2.

FIG. 9( a) is a track configuration of a type 1 disc showing allocationof recording and reproducing operation according to the presentinvention.

FIG. 9( b) is a track configuration of a type 2 disc showing allocationof recording and reproducing operation according to the presentinvention.

In FIGS. 9( a) and 9(b), track numbers 1 through 9 follow a trackarrangement from an inner circumferential track to an outercircumferential track in order. A wording “recording” in a “Track” lineunder the track number indicates that a track No. 1 is a recordingtrack, for example. A wording “pit” in a third line indicates that thereexisted a pit in a track. A wording “LPP” in a fourth line indicatesthat there existed an LPP on a land. A “Depth” is a cross sectional viewof respective tracks showing relative depth of respective tracks. InFIG. 9( a), each track of track numbers 1 and 2 of a type 1 disc is anarea of enabling to record and reproduce having a LPP, which possessesan information such as an address in a land area allocated to a side ofa groove area having a depth of approximately λ/12 in an outercircumferential direction. The track numbers 1 and 2 are equivalent tothe “initial zone”, the “system reserved zone”, the “buffer zone 0”, the“RW-physical format information zone”, the “reference code zone”, the“buffer zone 1”, and the “linking loss area” shown in FIG. 5, wherein atracking error signal by the differential push-pull method can beobtained from these zones and area. A wobbling signal is allocated toall the areas shown in FIGS. 5 and 9( a).

Each track of track numbers 3 and 4 of the type 1 disc is configured bya depth of approximately λ/4 and is the “control data zone” or the“readable emboss without LPP” area, which is the read only area ofenabling to read out a recorded signal, wherein a DPD tracking errorsignal composed of a pre-pit without a LPP can be obtained.

Each track of track numbers 5, 6, and 7 of the type 1 disc is configuredby a depth of approximately λ/12 and is the “unreadable emboss with LPP”area, which is the read only area of disabling to read out a recordedsignal, wherein a DPD tracking error signal composed of a pre-pit with aLPP can be obtained.

Each track of track numbers 8 and 9 of the type 1 disc is the “dataarea”, which is an area of enabling to record and reproduce, wherein atracking error signal by the differential push-pull method having a LPP,which possesses an information such as an address in a land areaallocated to a side of a groove area in an outer circumferentialdirection.

In FIG. 9( b), a track of track number 1 of a type 2 disc is an area ofenabling to record and reproduce having a LPP, which possesses aninformation such as an address in a land area allocated to a side of agroove area having a depth of approximately λ/12 in an outercircumferential direction. The track number 1 is equivalent to the“initial zone”, the “system reserved zone”, the “buffer zone 0”, the“RW-physical format information zone”, and the “reference code zone”shown in FIG. 5, wherein a tracking error signal by the differentialpush-pull method can be obtained from these zones.

A track of track number 2 of the type 2 disc is an intermediate area.

Each track of track numbers 3 and 4 of the type 2 disc is configured bya depth of approximately λ/4 and is the “control data zone” or the“readable emboss without LPP” area, which is the read only area ofenabling to read out a recorded signal, wherein a DPD tracking errorsignal composed of a pre-pit without a LPP can be obtained.

A track of track number 5 of the type 2 disc is another intermediatearea.

Each track of track numbers 6 and 7 of the type 2 disc is configured bya depth of approximately λ/12 and is the “unreadable emboss with LPP”area, which is the read only area of disabling to read out a recordedsignal, wherein a DPD tracking error signal composed of a pre-pit with aLPP can be obtained.

Each track of track numbers 8 and 9 of the type 2 disc is the “dataarea”, which is an area of enabling to record and reproduce, wherein atracking error signal by the differential push-pull method having a LPP,which possesses an information such as an address in a land areaallocated to a side of a groove area in an outer circumferentialdirection.

In the above-mentioned allocations, it is necessary for a disc to bejudged whether the disc is the type 1 or the type 2 when recording orreproducing. With respect to a detecting method of the type 1 or thetype 2, when a disc is loaded and processed to start, the disc is judgedwhether a value of the type 1 or the type 2 is recorded in the “controldata zone” of the disc having the above-mentioned lead-in information byreproducing the “control data zone”. Then the disc is judged by thevalue. The value can be read out by either a recording apparatus or areproducing apparatus as the same detecting method as mentioned above.Further, the value of type 1 or type 2 is recorded as a LPP in the“boundary flag zone 1” and the “boundary flag zone 2”, so that the disccan be judged by reading out the value when recording. This method canbe applied for a recording by a recording apparatus. This type ofrecording can be performed by any other method if the value can bedetected from a disc not recorded.

In a case that a disc of type 1 is recorded in tracks in an order of atrack number form the track number 1, that is, in the order of the“Write Mode” indicated in the left side of FIG. 5, each track of tracknumbers 1, 2, 8, and 9 is a track to be recorded. As mentioned above,there existed a wobbling frequency signal on both sides of each track inall areas. By detecting the frequency signal, and by feeding back avelocity signal for rotating the disc, the disc is controlled by aconstant linear velocity and a recording clock signal is produced.Succeedingly, a LPP recorded in a land is detected and an address signalis produced. A recording starts at a predetermined linking timing of thetrack in accordance with the produced address signal. In other words, arecording of the “initial zone” through the “linking loss area” inaccordance with the “Write Mode” shown in the left side of FIG. 5starts. Further, the recording is interrupted at a linking timing of anaddress corresponding to the track number 3 and the “Write Mode” is in areading mode.

The track of the track number 3 is composed of a pit of enabling toreproduce a recording area without a LPP signal. An address is detectedfrom the pit of enabling to reproduce and the “control data zone” or the“readable emboss without LPP” area is reproduced as far as the tracknumber 4.

Each track of track numbers 5 through 7 is a track, wherein a signal ofa pit can not be reproduced. However, since a wobble signal and a LPPsignal is existed in the area, the wobble signal and the LPP address isreproduced while reproducing the track, and then a recording clock andrecording timing signals are produced. This is corresponding toreproducing the “unreadable emboss with LPP” area in accordance with the“reading gen wclk” mode of the “Write Mode” shown in the left side ofFIG. 5. In tracks of the track number 8 and above, a recording starts ata linking timing as same as the preceding track and performs a recordingprocess thereafter. This is corresponding to recording the “buffer zone2” and the “data area” in accordance with the “recording” mode of the“Write Mode” shown in the left side of FIG. 5.

On the other hand, in a disc of type 1, both side of each track issymmetrical with respect to a center axis of the track. Tracking errorsignals by the differential push-pull at a boundary of each track of thetrack numbers 2 and 3, each track of the track numbers 4 and 5, and eachtrack of the track numbers 7 and 8 can be continuously obtained withinsome extent of amplitude difference.

As mentioned above, since a boundary of pit area can be continuouslyrecorded, an RF signal can continuously be obtained while reproducing.Further, a process while reproducing shown as the “Read Mode” in theleft side of FIG. 5 is performed by obtaining a tracking error signal bythe DPD method, in some cases, the differential push-pull method canalso be acceptable, and tracks of the track number 1 through the tracknumber 9 are reproduced in order. In other words, zones including the“initial zone” through the “control data zone” are reproduced as shownby the “reading” of the “Read Mode” in the left side of FIG. 5. Duringthis process, a signal of each track of the track numbers 5, 6, and 7can not be reproduced, so that these tracks are skipped. This iscorresponding to the “seek” mode of the “unreadable emboss with LPP”area and the “buffer zone 2” in the “Read Mode” shown in the left sideof FIG. 5. Tracks of the track number 8 and above are continuouslyreproduced thereafter, that is, the “data area” is reproduced inresponse to the “reading” mode in the “Read Mode” shown in the left sideof FIG. 5.

When recording a disc of type 2 in tracks of track number 1 and above inorder, each track of track numbers 1, 8, and 9 is a track to berecorded. In a disc of type 1, a track of track number 2 is a recordabletrack. However, in a disc of type 2, a track of track number 2 is anintermediate area or a track having a pit. It is caused by that depthsof lands allocated both sides of the track are different from each otherin a track of track number 2 of a disc of type 2. Therefore, a signalcan not be obtained by signal amplitude and an offset level of thesignal equivalent to those of a preceding track, although a wobble andLPP signals necessary for recording are recorded. Further, a recordingclock signal and a timing signal may not be accurately obtained.

A track of track number 5 is also an intermediate area as same as thetrack number 2. In a track of track number 5 of a disc of type 2, depthsof lands allocated both sides of the track are different from eachother. Therefore, a signal can not be obtained by signal amplitude andan offset level of the signal equivalent to those of a preceding track,although a wobble and LPP signals necessary for recording are recorded.Further, a recording clock signal and a timing signal may not beaccurately obtained. Accordingly, obtaining the recording clock signaland the timing signal can be performed at a track of track number 6 andabove

A sequence of recording process shown in the “Write Mode” in the rightside of FIG. 5 is depicted next. In a track of track number 1, thereexisted a wobbling frequency signal on both sides of a track asmentioned above. By detecting the frequency signal, and by feeding backa velocity signal for rotating the disc, a recording clock signal isproduced in conjunction with controlling the disc in a constant linearvelocity. Succeedingly, a LPP recorded in a land is detected and anaddress signal is produced. At a predetermined linking timing of thetrack in accordance with the produced address signal as a timing signal,a “recording” mode of recording the “initial zone” through the “boundaryflag zone 1” in the “Write Mode” shown in the right side of FIG. 5starts.

The “recording” mode is interrupted and changed into a reproducing modeat a linking timing of an address corresponding to the track of tracknumber 2. Since a recording area of the track of track number 2 iscomposed of a pit of disabling or enabling to reproduce, reading thetrack is skipped over. This process is skipping the “boundary embosszone 1” shown by an arrow with a broken line succeeding the “recording”mode of the “Write Mode” in the right side of FIG. 5. A recording areaof a track of track number 3 is composed of a pit of enabling toreproduce without a LPP signal. An address is detected from a pit ofenabling to reproduce and tracks up to the track number 4 are reproducedin accordance with the address. This process is reproducing the “controldata zone” or the “readable emboss without LPP” area and the “boundaryflag zone 2” in the “reading” mode of the “Write Mode” shown in theright side of FIG. 5.

In a track of track number 5, a signal of pit may not be reproduced or aLPP signal may not be accurately reproduced, so that reproducing thetrack is skipped over. Each track of track numbers 5 through 7 is atrack, wherein a signal of a pit can not be reproduced. However, since awobble signal and a LPP signal is existed in the area, the wobble signaland the LPP address is reproduced while reproducing the track, and thena recording clock and recording timing signals are produced. Thisprocess is corresponding to reproducing the “unreadable emboss with LPP”area in the “reading gen wclk” mode of the “Write Mode” shown in theright side of FIG. 5. In tracks of the track number 8 and above, arecording mode starts at a linking timing as same manner as thepreceding track and a recording process is performed thereafter. Thisprocess is corresponding to recording the “buffer zone 2” and the “dataarea” in the “recording” mode of the “Write Mode” shown in the rightside of FIG. 5.

In a disc of type 2, tracks of track numbers 2 and 5, which areintermediate areas at both sides of the track, are asymmetrical withrespect to a center axis. At a boundary of the track, a tracking errorsignal by the differential push-pull system can be continuously obtainedwithin some extent of amplitude difference although the tracking errorsignal can not be accurately recorded or reproduced due to the amplitudedifference or generating offset.

Boundaries of pit areas can be continuously recorded if the areas areallocated as mentioned above, so that an RF signal can be continuouslyobtained while reproducing. A reproducing process, which is shown in the“Read Mode” in the right side of FIG. 5, is performed by reproducingtracks of track numbers 1 through 9 in order for obtaining a trackingerror signal by either the DPD method or the differential push-pullmethod. In a disc of type 2, since a signal of each track of tracknumbers 2, 5, 6, and 7 can not be reproduced, reproducing the tracks isskipped over. The process is a seek mode of seeking the “initial zone”through the “boundary emboss zone 1” and the “boundary flag zone 2”through the “buffer zone 2” as shown by the “seek” of the “Read Mode” inthe right side of FIG. 5. Each track of track numbers 3, 4, 8, and aboveis continuously reproduced thereafter. This process is a reproducingmode of reproducing the “control data zone” or the “readable embosswithout LPP” area through the “boundary flag zone 2” and the “data area”as shown by the “reading” of the “Read Mode” in the right side of FIG. 5

In a case that a type of a disc can not be detected and is decided asthe type 1, or in a case that a disc of type 2 is accidentally detectedas the type 1, the present invention is effective for these kind ofincorrect detection. In other words, in these cases, a recordingapparatus tries to perform a recording process on the track of tracknumber 2. However, by the track number 2, an LPP signal can notaccurately be detected although a wobble signal is detected, so thateither the recording process is interrupted or the recording process isperformed with interpolating the LPP signal by a signal processingcircuit. If the track of track number 2 is recorded totally, since atracking error signal can be obtained from the area while reproducingthe track, the area can be continuously reproduced without any problemalthough a reproduction signal can not be read out from the track oftrack number 2. Further, an LPP signal may not be read out from a trackof track number 5. However, an LPP signal can be read out from asucceeding track, so that a recording and reproducing process can becontinuously performed without any problem.

Second Embodiment

FIG. 6( a) is a partially enlarged cross sectional view of a resistboard of an information recording medium according to a secondembodiment of the present invention.

FIG. 6( b) is a partially enlarged plan view of the resist board shownin FIG. 6( a).

An information recording medium of the second embodiment is very similarto that of the first embodiment. Therefore, differences from the firstembodiment are explained hereto. An information recording mediumaccording to the second embodiment of the present invention is arecordable optical disc having a disc substrate formed with a resistboard 200 shown in FIGS. 6( a) and 6(b). In FIG. 6( a), the recordableoptical disc is composed of a read only area P201, arecording/reproducing area A201 formed with a guide groove “1” and anintermediate area, which is formed between the areas P201 and A201.

As shown in FIGS. 6( a) and 6(b), bottoms of pit arrays PAa through PAc(hereinafter generically referred to pit array PA) in the area P201 anda pit array PM in the intermediate area are in a same flat level,wherein each bottom of pit arrays faces toward a glass substrate 101.

A pit depth, that is, an optical pit depth of the pit array PM to abottom of the pit array PM in the intermediate area is constituted so asto decrease, for example, from an optical depth “c” of a land L201 to anoptical depth “d” of a land L202 as shown in FIGS. 6( a) and 6(b).

Third Embodiment

FIG. 10 shows a configuration of a lead-in area and a data area of aninformation recording medium according to a third embodiment of thepresent invention.

A major difference between FIG. 5 and FIG. 10 is such that the “bufferzone 1” of the type 2 shown in FIG. 5 is referred to an “unreadableemboss with LPP boundary flag 1” area in FIG. 10. In this case, a wobblesignal is recorded in all areas and the wobble signal can be obtainedfrom all the areas. This type of disc is defined as a type 3. Withrespect to recording and reproducing operations of a type 3 disc, theoperations of recording and reproducing are shown by a “Write Mode” anda “Read Mode” respectively in the right side of FIG. 10. Theseoperations of the type 3 is a same as those of the type 2 except for the“unreadable emboss with LPP boundary flag 1” area. Therefore, the sameoperation as that of the type 2 is omitted from a description of thetype 3. A different operation from the type 2 is as follows.

An area of the “unreadable emboss with LPP boundary flag 1” is a same asthe area of the “unreadable emboss with LPP”. The “boundary flag 1” iswritten in an LPP of the area of “unreadable emboss with LPP boundaryflag 1” or in a “control data zone”. In FIG. 10, since the “boundaryflag 1” is recorded in the “unreadable emboss” area instead of recordingin the “buffer zone 1” basically, a recording process finishes at a“reference code zone” preceding the “unreadable emboss with LPP” areaand is changed over to a reproducing operation. Further, a “boundaryflag 2” is written in the “control data zone”, In addition thereto,recording and reproducing operations of type 1 in FIG. 10 are a same asthose of the type 1 in FIG. 5, so that a description of the type 1 isomitted.

Fourth Embodiment

FIG. 11( a) shows a configuration of a lead-in area and a data area ofan information recording medium according to a fourth embodiment of thepresent invention.

FIG. 11( b) is a comparison table showing differences between a type 4and a type 5 shown in FIG. 11( a), wherein wording “WBL” represents“wobbling”. In this configuration, a wobble signal is recorded in allareas and the wobble signal can be obtained from all the areas. In FIG.11( a), the type 4 and the type 5 is provided with both the “boundaryemboss zone 1” and the “boundary emboss zone 2” of the type 2 shown inFIG. 5, which are allocated at the same addresses common to the type 1and the type 2 shown in FIG. 5. As mentioned above, the “boundary embosszone 1” and the “boundary emboss zone 2” is an area composed of anemboss pit shown in a comparison table in FIG. 11( b). In the type 4,wobble and LPP signals are recorded. On the other hand, in the type 5, awobble signal is recorded. However, it is not required for the type 5 tobe recorded with an LPP. Further, an LPP signal can not be accuratelyread out from the area of the “boundary emboss zone 1” and the “boundaryemboss zone 2” although the LPP signal is recorded in the area.Furthermore, it is not necessary for an emboss pit in the area whetheror not the emboss pit can reproduce a data. An identificationinformation for indicating the type 4 or type 5 is prerecorded in an LPPsignal or in a readable read only area such as the “control data zone”.

By formatting as mentioned above, recording and reproducing operationsshown by the “Write Mode” and the “Read Mode” in the left side of FIG.11( a) are as follows: the “Write Mode” starts with recording a “initialzone” through a “liking loss area”, the “Write Mode” is changed into a“reading” mode and a wobble signal is read out from an “unreadableemboss with LPP” area, a clock signal for recording is produced, anaddress signal is produced from the LPP and a timing for recording isproduced in a “reading gen wclk” mode, and then another reading modestarts from a “buffer zone 2”. In addition thereto, the “Read Mode” isthe same as that of the second embodiment. Accordingly, a description ofthe “Read Mode” is omitted.

As mentioned above, exactly the same recording and reproducing methodcan be applied to a disc of either the type 4 or type 5, so thatdesigning a device or an apparatus can be easier. In a case of the type4, as mentioned above, a tracking signal can be obtained by either thepush-pull or the differential push-pull method without any problem. Onthe other hand, in a case of the type 5, a tracking signal can beobtained by the differential push-pull method. However, by the push-pullmethod, it is hard to pass through the “boundary emboss zone 1” and the“boundary emboss zone 2” continuously. By prerecording an identificationinformation for identifying the type 4 or type 5 such as a “type 4 flag”and a “type 5 flag” in a LPP or in a read only area such as a readable“control data zone”, an appropriate method can be applied to arespective disc of type 4 or type 5.

Types of discs explained in each embodiment are classified hereto. Sincethe type 1 and the type 4 belongs to a same group, the type 1 representsgenerically the group hereinafter. Further, the type 2, type 3, and type5 is classified into another group, so that the type 2 genericallyrepresent the other group hereinafter. By configuring a lead-in area anda data area as mentioned above, two different manufacturing methods forthe type 1 and type 2 can be allowed. Further, a tracking error signalcan be continuously obtained when recording or reproducing a disc.Therefore, a recording or reproducing can be continuously performedwithout interruption. Accordingly, a DVD-RW disc can be increased inperformance on value added without affecting a currently availablereproducing apparatus for a DVD-ROM disc or a DVD video disc.

Furthermore, in the above-mentioned embodiments, the “boundary embosszone 1” and the “boundary emboss zone 2” composed of a pit area of onetrack respectively is provided as an intermediate area allocated eitherbetween a read only area and a recording area or between a read onlyarea and another read only area. However, It is apparent that theintermediate area can be composed of more than two tracks. As seen fromFIG. 5, difference between the type 1 and the type 2 is minor. Withdefining such that both the “boundary emboss zone 1” being a boundarybetween a recording area and a read only area and the “boundary embosszone 2” being another boundary between a first read only area and asecond read only area are a boundary, which is not necessary to berecorded if an address can not be detected accurately, or which is notnecessary to read out a reproduction signal accurately, the type 1 andthe type 2 can be unified into a common format.

Fifth Embodiment

FIG. 12( a) shows a configuration of a lead-in area and a data area ofan information recording medium according to a fifth embodiment of thepresent invention.

FIGS. 12( b) through 12(d) are comparison tables showing differences instructure between a type 6 and a type 7. In FIGS. 12( c) and 12(d), awording WBL indicates wobbling.

In this configuration, a wobble signal is recorded in all areas and thewobble signal can be obtained from all the areas. In FIG. 12( a), thetype 6 and the type 7 is corresponding to the type 4 shown in FIG. 11(a) with replacing the “boundary emboss zone 1” with a “boundary zone 1”.In the type 6, the “boundary zone 1” is assigned to be a recordablegroove area, which is recorded with a wobble signal and a LPP. In thetype 7, the “boundary zone 1” is assigned to be an emboss pit area,which is recorded with a wobble signal but not recorded with a LPP.Further, a “boundary emboss zone 2” shown in FIG. 12( a) is assigned tobe another emboss pit area, which is recorded with a wobbling signal anda LPP as same as those recorded in the “boundary emboss zone 1” and the“boundary emboss zone 2” in FIG. 11( a). In a case of the type 7, the“boundary emboss zone 2” is an area, wherein it is acceptable that a LPPcan not be read out accurately although the LPP is recorded. Anidentification information such as a “type 6 flag” and a “type 7 flag”for identifying the type 6 or type 7 is prerecorded in a LPP or in aread only area such as a readable “control data zone”.

By defining an area as mentioned above, the type 6 and the type 7 can beunified into a common format. Since there existed two cases of recordingthe area and reproducing the area then, by prerecording a wobble signalin the area although an address signal is not recorded in a LPP of thearea, a speed signal of a spindle can be produced and an address signalof the LPP can be recorded by interpolating the address signal by usinga specific circuit. Actually, in a case of recording the “boundary zone1”, as shown in FIG. 12( b), an ECC block of a latter half of two ECCblocks is assigned to be a “linking loss area” for the type 6 and arecording is performed up to the “linking loss area”. In a case of thetype 7, an ECC block of a first half of the two ECC blocks is assignedto be the “linking loss area” and a recording is performed up to the“linking loss area”.

Further, by prerecording a wobble signal in the “boundary emboss zone 2”for a same reason as mentioned above, a recording clock signal forrecording can be produced continuously and a speed signal for a spindlecan also be produced. Accordingly, a recording and reproducing processcan be assured with maintaining interchangeability between the type 6and type 7. In this case, an offset signal may generate in a push-pullsignal in an intermediate area and an offset signal in DC (directcurrent) may generate in a wobble signal. By using a certain method suchthat the offset signal is passed through a band pass filter, a wobblesignal can be continuously obtained without any dropout, or the wobblesignal can be formed with a minor dropout in a short period of time.Therefore, an affection of offset can be eliminated by interpolatingcontinuity of a wobble signal by using a specific circuit. Byconfiguring as mentioned above, interchangeability can be furthermaintained while recording and reproducing and a manufacturing method oftwo types of discs can be realized. Accordingly, such the format isadvanced and promoted furthermore.

In addition thereto, it is common to all the embodiments that the“boundary emboss zone 1” or the “boundary zone 1” is formed as a pit inan intermediate area equivalent to one round of a disc. However, two ECCblocks allocated as the intermediate area is a larger area than oneround of a disc slightly. Therefore, some sectors or some sync frames ofthe latter half of the ECC blocks are a readable area as same as the“control data zone” following the “boundary emboss zone 1” or the“boundary zone 1”. Further, the area is provided with at least two syncframes, so that the “control data zone” can be read out from a head ofthe zone accurately by drawing a reproduction signal into a PLL (phaselocked loop) circuit or by performing the sync detection between the twosync frames when reproducing the “control data zone”. The “boundaryemboss zone 2” is also formed as a pit in an intermediate areaequivalent to one round of a disc. Two ECC blocks, which are allocatedas the intermediate area, are a larger area than one round of a discslightly. Accordingly, some sectors or some sync frames of the latterhalf of the ECC blocks are a readable area of enabling to read out awobble signal and a LPP signal as same as the “unreadable emboss zone”following the “boundary emboss zone 2”.

By formatting as mentioned above, an LPP or an information about thetype 6 or the type 7 recorded in the “control data zone” is obtained bythe “Write Mode” (recording operation) and the “Read Mode” (reproducingoperation) shown in the left side of FIG. 12( a), wherein a same processas described in the embodiments mentioned above is omitted. In a case ofthe “Write Mode” of the type 6, the “Write Mode” performs recording upto a “linking loss area”, which is a last ECC block of the “boundaryzone 1”, and then the “recording” mode is switched over to a “reading”mode. In the “reading gen wclk” mode, a wobble signal is read out fromthe “unreadable emboss with LPP” area and a clock for recording isproduced, and then an address signal is produced from a LPP and a timingfor recording is produced. After that, a “recording” mode starts againfrom the “buffer zone 2”. In a case of the “Write Mode” of the type 7,the “Write Mode” performs recording up to a “linking loss area”, whichis a last ECC block preceding the “boundary zone 1”, and then the“recording” mode is switched over to a “reading” mode. In the “readinggen wclk” mode, a wobble signal is read out from the “unreadable embosswith LPP” area and a clock for recording is produced, and then anaddress signal is produced from a LPP and a timing for recording isproduced. After that, a “recording” mode starts again from the “bufferzone 2”. If a recording medium of the type 7 is recorded by the methodfor the type 6 with assuming the recording medium as the type 6 withoutobtaining the information of the type 6 or type 7 recorded in the LPP orthe “control data zone”, the recording medium can be continuouslyrecorded in accordance with a wobble signal, which can be continuouslyobtained, even though an LPP signal can not be obtained. In thisparticular case, a recorded signal can not be read out from the areawhen the area is reproduced. However, the recorded signal is aninformation of one track and is not an information recorded in animportant information area, so that no problem may happen. In additionthereto, the “Read Mode” is a same as that of other embodimentsmentioned above, so that its description is omitted.

Sixth Embodiment

FIG. 13( a) is a partially enlarged cross sectional view of a resistboard of an information recording medium according to a sixth embodimentof the present invention in a cutting state.

FIG. 13( b) is a partially enlarged plan view of the resist board shownin FIG. 13( a).

In the embodiments mentioned above, a bottom of each track is configuredin a same depth. However, in the sixth embodiment shown in FIG. 13( a),an intermediate area (P603) is composed of guide grooves 6 a through 6 e(hereinafter generically referred to guide groove 6) having a differentdepth. A bottom of a guide groove area P603 gradually becomes shallowerin a predetermined gradient from a direction of a guide groove area P602(having guide grooves 1A through 1 c) to a direction of a pit array areaP601 having pit arrays PAa through PAc and a bottom of the pit arrayarea P601 is a same as that of the guide groove area P602. Difference ofa method of manufacturing such the depth configuration of the sixthembodiment from that of the prior art is as follows.

In the intermediate area P603 as a transitional area from the guidegroove area P602 to the pit array area P601, wherein a bottom of a trackis allocated on the top surface of a glass substrate 101, a condition ofcutting a guide groove and a LPP by exposing a resist board 600 as deepas the top surface of the glass substrate 101 is utilized as an initialcondition. A laser beam “A” contains a wobble signal. The laser beam “A”is swung or wobbled right and left horizontally by a light polarizingdevice (not shown) so as to be an amplitude of 15 nm on the resist board600. An intensity of the laser beam “A” is regulated to an intensity PA3such that a width of the guide groove “1” becomes 0.3 μm and a depth ofthe groove becomes approximately 30 nm. On the other hand, a laser beam“B” is regulated to an intensity PB3 so as to form a LPP (land pre-pit)in a depth of approximately 30 nm. A cutting process is performed by theconstant linear velocity (CLV) method. A turntable (not shown) iscontrolled such that one rotation of the resist board 600 is equivalentto one track pitch and makes a movement of constant velocity by 0.74 μmfrom an inner circumference to an outer circumference of the resistboard 600. Each output of the laser beams “A” and “B” is continuouslychanged while cutting a slanted portion of 3 tracks. While cutting theslanted portion, the laser beam “A” is controlled to be a specific beamstrength suitable for recording a guide groove having a bottom of notreaching the top surface of the glass substrate 101, wherein a bottom ofa guide groove is not exposed until the top surface of the glasssubstrate 101. A wobble signal shifts or wobbles the laser beam “B”right and left horizontally by a light polarizing device (not shown) soas to be an amplitude of 15 nm on the resist board 600. An intensity ofthe laser beam “B” is regulated to an intensity such that a width of aguide groove becomes 0.3 μm and a depth of the groove becomesapproximately 30 nm. Further, the laser beam “B” is controlled toincrease continuously up to specific beam strength suitable for forminga LPP on a side of a guide groove.

In the intermediate area P603 as a transitional area from the pit arrayarea P601 to the guide groove area P602, wherein a bottom of a guidegroove is allocated on the top surface of the glass substrate 101, it isdefined as an initial condition such that the laser beam “A” iscontrolled to increase its beam strength continuously up to specificbeam strength suitable for recording a guide groove, which is exposeduntil the top surface of the glass substrate 101, while cutting aslanted portion of 3 tracks by certain beam strength suitable forrecording a guide groove having a bottom of not reaching the top surfaceof the glass substrate 101. With respect to the laser beam “B”, its beamstrength is continuously changed from certain beam strength suitable forforming a desired LPP to specific beam strength designated to form a LPPto be cut having a depth of approximately 30 nm while cutting a slantportion of 3 tracks.

In a track of a recordable intermediate area having a slant of a discproduced by the method mentioned above, offset may happen slightly by atracking system of either the push-pull method or the differentialpush-pull method. However, the track can be recorded and reproduced.Since the track can not be recorded by the push-pull method as mentionedabove, it is not necessary for the track to be composed of a pre-pit.Accordingly, the track can be designated to be a recordable area.Further, a tracking can be stably performed by the DPD method withoutany problem such as offset after the track as the recordable area isrecorded. In the aforementioned embodiment, if an intermediate areacomposed of a pit area is overwritten, or due to a pit shape in theintermediate area, offset may happen by the DPD method. However, in thesixth embodiment, this kind of problem can be solved. Furthermore, botha wobble signal and an address signal of a LPP can be previously formedin the intermediate area. Accordingly, a recording operation of a signalto be recorded can almost accurately be performed and a reproducingoperation of a reproduction signal can also stably be performed.

FIG. 14( a) shows a configuration of a lead-in area and a data area ofthe information recording medium according to the sixth embodiment ofthe present invention. FIGS. 14( b) and 14(c) are comparison tablesshowing differences between a type 6 and a type 8. In FIGS. 14( b) and14(c), a wording WBL indicates wobbling.

In this configuration shown in FIGS. 14( a) through 14(c), a wobblesignal is recorded in all areas and the wobble signal can be obtainedfrom all the areas. A type 6 shown in FIG. 14( a) is substantially asame as the type 6 shown in FIGS. 12( b) and 12(c). Further, in a caseof the type 7 shown in FIG. 12( c), the “boundary zone 1” is notrecorded with an LPP as an emboss pit area although wobbling (WBL) isrecorded in there. On the other hand, in a case of a type 8 shown inFIG. 14( a), a “boundary zone 1” is an area, which is slanted asmentioned above and recorded with wobbling (WBL) and an LPP as arecordable groove area, wherein it is not necessary for an LPP to beread out accurately although the LPP is allocated in the area.Furthermore, in a case of the type 7 shown in FIG. 12( d), the “boundaryemboss zone 2” is recorded with WBL and an LPP as an emboss pit area.However, in a case of the type 8 shown in FIG. 14( c), an “boundaryemboss zone 2” is an area, wherein it is not necessary for an LPP to beread out accurately although the LPP is recorded in the area. Anidentification information for identifying the type 6 or the type 8 isprerecorded in an LPP or in a read only area such as a “control datazone”. The identification information can be defined by writing a codesuch as “0”: without boundary and “1”: with boundary, for example, in a“Media type 3” of a “Disc physical code” in an LPP information.

If the area is defined as mentioned above, the type 6 and the type 8 canbe unified into a common format. In two cases of recording the area andreproducing the area then, a speed signal for a spindle can be producedby a wobble signal although an address signal of an LPP can not bedetected in the intermediate area. Further, an address signal of the LPPcan be recorded by interpolating the address signal by using a specificcircuit. Actually, in a case of recording the “boundary zone 1”, an ECCblock at an address of “2F1F0h” is assigned to be a “linking loss area”for both the type 6 and the type 8, and then a recording is performed upto the “linking loss area”.

Further, by prerecording a wobble signal in the “boundary emboss zone 2”for a same reason as mentioned above, a recording clock signal forrecording can be produced continuously and a speed signal for a spindlecan also be produced. Accordingly, a recording and reproducing processcan be assured with maintaining interchangeability between the type 6and type 8. In this case, an offset signal may generate in a push-pullsignal in an intermediate area and an offset signal in DC may generatein a wobble signal. By using a certain method such that the offsetsignal is passed through a band pass filter, a wobble signal can becontinuously obtained without any dropout, or the wobble signal can beformed with a minor dropout in a short period of time. Therefore, anaffection of offset can be eliminated by interpolating continuity of awobble signal by using a specific circuit. By configuring as mentionedabove, interchangeability can be further maintained while recording andreproducing and a manufacturing method of two types of discs can berealized. Accordingly, such the format is advanced and promotedfurthermore.

By formatting as mentioned above, an LPP or an information about thetype 6 or the type 8 recorded in the “control data zone” is obtained bythe “Write Mode” (recording operation) and the “Read Mode” (reproducingoperation) shown in the left side of FIG. 14( a), wherein a same processas described in the embodiments mentioned above is omitted. In a case ofthe “Write Mode” of the type 6 and the type 8, the “Write Mode” isperformed by recording up to a “linking loss area”, which is a last ECCblock of the “boundary zone 1”, and then the “recording” mode isswitched over to a “reading” mode. In the “reading gen wclk” mode, awobble signal is read out from the “unreadable emboss with LPP” area anda clock for recording is produced, and then an address signal isproduced from an LPP and a timing for recording is produced. After that,a “recording” mode starts again from the “buffer zone 2”. Further, in acase of recording the “boundary zone 1” by the type 8 and using thepush-pull method for tracking error, an offset signal generates in atracking error signal within a permissible range. Therefore, bymeasuring an offset value previously when recording the “boundary zone1”, the “boundary zone 1” can be accurately recorded with controlling tocancel offset in response to the offset value. Furthermore, if arecording medium of the type 8 is recorded by the method for the type 6with assuming the recording medium as the type 6 without obtaining theinformation of the type 6 or the type 8 recorded in the LPP or the“control data zone”, the recording medium can be continuously recordedin accordance with a wobble signal, which can be continuously obtained,even though an LPP signal can not be obtained.

Seventh Embodiment

FIG. 15 is a waveform of a tracking error signal according to a seventhembodiment of the present invention.

In this seventh embodiment of the present invention, it is depicted thata type of a disc equivalent to that of the sixth embodiment shown inFIGS. 14( a) through 14(c) is defined as the type 1 of the firstembodiment shown in FIG. 5. Difference of the seventh embodiment fromFIGS. 5 and 14( a) through 14(c) is as follows with considering thedifferences macroscopically. The type 6 shown in FIGS. 14( a) through14(c) is corresponding to the type 6 shown in FIGS. 12( a) through12(d). Further, the type 6 is substantially the same as the type 1 shownin FIG. 5 except for some zone names. In other words, the type 8 shownin FIGS. 14( a) through 14(c) is assigned to be a recordable groovearea, which is slanted as mentioned above and recorded with WBL and anLPP, and to be a same area as the “buffer zone 1” of the type 1.Therefore, the type 8 can be defined or called as the “buffer zone 1”.Similarly, the “boundary emboss zone 2” shown in FIGS. 14( a) through14(c) is an emboss pit area recorded with WBL and an LPP and is a samearea as the “unreadable emboss with LPP” area. Therefore, the boundaryemboss zone 2″ can be defined or called as the “unreadable emboss withLPP” area, wherein a reproduction signal can not be read out accuratelyfrom the area although an LPP signal can be read out. Further, the“unreadable emboss with LPP” area is utilized for servo controlling, sothat the area can be called a “servo block”.

By the above-mentioned definition, the type 6 and the type 8 shown inFIGS. 14( a) through 14(c) can use the same drawing as the type 1 shownin FIG. 5. However, the flags for indicating the type 6 and the type 8are not existed in FIG. 5. Further, in two boundaries, where twoboundary zones of the “boundary zone 1” and the “boundary emboss zone 2”are allocated, a tracking error signal particularly by the push-pullmethod may be different from an amplitude level and an offset level in aregular signal area, wherein a boundary track of the boundaries are suchas a track between the “buffer zone 1” of a recordable area and the“control data zone” composed of a pit and one or more tracks allocatedadjacent to another boundary between the “control data zone” and the“unreadable emboss with LPP” area of a read only track in which areproduction signal composed of a pit can not be accurately read outfrom the area. By using the type 1 shown in FIG. 5, these two boundariesare expressed in other words. The two boundaries are such that a trackbetween the “buffer zone 1” including the “linking loss area” being arecordable area and the “control data zone”, which is composed of a pit,and one or more tracks allocated adjacent to another boundary betweenthe “control data zone” and the “unreadable emboss with LPP” area beinga read only track, wherein a reproduction signal composed of a pit cannot be accurately read out. In these two boundaries, a tracking errorsignal particularly by the push-pull method may be different from anamplitude level and an offset level in a regular signal area.

In a recordable area and a read only area, amplitude of the trackingerror signal by the push-pull method is basically different from eachother. Amplitude of a tracking error signal is defined in the respectiveareas. As shown in FIG. 15, when a laser beam crosses a trackparticularly in a tracking off mode, amplitude of a tracking errorsignal by the push-pull method in a recordable area is designated suchthat a peak value in an upward direction is P1 and another peak value ina downward direction is P2 with standardizing a center voltage. Further,in a boundary between a pit area and the recordable area, peak values inan upward direction and a downward direction are defined as P3 and P4respectively. Relations among the P1 through P4 are as follows:P3/(P1+P2)>0.2 and P4/(P1+P2)>0.2.

The value 0.2 is necessary for stabilizing controls such as trackingwhile recording or reproducing the areas shown in FIG. 15 even when atracking error signal by the push-pull method becomes smaller.Furthermore, the value 0.2 may vary by a measuring method, so that arange of 0.15 through 0.3 approximately is more desirable.

For instance, in a readable area other than the boundary shown in FIG.15, an offset amount of amplitude of a tracking error signal is definedby a formula (P1−P2)/(P1+P2) as the asymmetry standard. When these twoboundaries are defined by using the formula, in a case that amplitude ofP1 and P2 are symmetrical with each other as shown in FIG. 15 and theiramplitude are as small as unlimitedly, the formula (P1−P2)/(P1+P2) issatisfied. However, there existed a problem such that a tracking servobecomes unstable. In a case that amplitude of P3 and P4 are symmetricalwith each other and their amplitude are small enough within a range ofmaintaining a tracking servo stable to the contrary, a disc can not besatisfied by a value of the formula (P1−P2)/(P1+P2). Therefore, a marginof manufacturing a disc is deteriorated. Accordingly, defining theboundary by introducing the two inequalities mentioned above is mostdesirable for a disc according to the seventh embodiment of the presentinvention.

By formatting mentioned above, the “Write Mode” (recording operation)and the “Read Mode” (reproducing operation) shown in FIG. 5 is performedin a sequence of operations shown in the left side of FIG. 5. However,at a time when a disc is discriminated as the disc of the type accordingto the seventh embodiment, the “Write Mode” performs recording up to the“linking loss area” with designating the “buffer zone 1” as the “linkingloss area” of a last ECC block, wherein the “buffer zone 1” isequivalent to the “boundary zone 1” shown in FIG. 14( a). Further, anarea adjacent to the “linking loss area” is a boundary as mentionedabove. In a case that amplitude of a tracking error signal is small, anoffset level of the tracking error signal may be different from that ofother tracks. Therefore, by changing a gain and an offset control valueduring a tracking control, only when recording the boundary, a recordingcontrol can be performed stably. Furthermore, the offset control valuecan be altered by a result of reviewing an offset level of a trackingerror signal previously measured in the boundary. The “Write Mode” ischanged over to the “reading” mode thereafter, the “control data zone”is reproduced. Then, in the “reading gen wclk” mode, a wobble signal isread out from the “unreadable emboss with LPP” area, a clock forrecording is produced, an address signal is produced from the LPP, andtiming for recording is produced. Succeedingly, the “recording” moderestarts from the “buffer zone 2.” An area covering the “control datazone” through the “unreadable emboss with LPP” area is also a boundary.In a case that amplitude of a tracking error signal in this boundary issmall, an offset level of the tracking error signal may be differentfrom that of other tracks. Therefore, by changing a gain and an offsetcontrol value during a tracking control, only when reading thisboundary, a recording control can be performed stably. Further, theoffset control value can be altered by a result of reviewing an offsetlevel of a tracking error signal previously measured in this boundary.At a time when a disc is discriminated as the disc of the type accordingto the seventh embodiment, it is a regular method for the “control datazone” when being reproduced. The method is such that the “Read Mode”shown in FIG. 5 moves in a neighborhood of the “linking loss area” beinga last ECC block of the “buffer zone 1” and a first area of the “controldata zone” is reproduced, wherein the “buffer zone 1” is equivalent tothe “boundary zone 1” shown in FIG. 14( a). In this case, an areaadjacent to the “linking loss area” is a boundary as mentioned above. Ina case that amplitude of a tracking error signal in this boundary issmall, an offset level of the tracking error signal may be differentfrom that of other tracks. Therefore, by changing a gain and an offsetcontrol value during a tracking control and by performing a recordingcontrol stably only when reading this boundary, the boundary can bepassed through without any problem. Further, the offset control valuecan be altered by a result of reviewing an offset level of a trackingerror signal previously measured in this boundary. In addition thereto,the boundary is recorded with an information having no meaning such as adata of totally “0” (zero). Therefore, the boundary can be skipped eventhough a data read out from the boundary becomes error. Accordingly,reproducing the “control data zone” obtains a necessary lead-ininformation and other information related to copyright protection, andthen moving to the “data area” performs a reproduction process ofcontents.

While the invention has been described above with reference to specificembodiments thereof, it is apparent that many changes, modifications andvariations in the arrangement of equipment and devices and in materialscan be made without departing from the invention concept disclosedherein. For example, two boundaries are mentioned above. They can beexisted both together or either one individually. Further, a boundary iseither an area such as an intermediate area and a transitional area or aboundary between two areas. A tracking error in a boundary is differentfrom that in respective two areas adjacent to the boundary. In additionthereto, a manufacturing method, configurations, and names of zones andareas are just utilized for explaining one embodiment. Accordingly, thepresent invention is not limited to such a manufacturing method, errorcorrection format, and a disc configuration for one embodiment.

According to the aspect of the present invention, a boundary is providedeither between a read only area and a recording area or between a readonly area and another read only area, or a boundary is definedpreviously. A recording and reproducing signal characteristic can beimproved. Further, the present invention is advantageous to eliminateproblems such that an excessive offset signal may generates in atracking error signal, a tracking error signal may drop off, andtrackability may decrease while recording. Furthermore, the presentinvention has an advantage of such that a disc in a different type canalso be recorded or reproduced without any problem.

1. An information recording medium having an information track formedspirally or in coaxial circles comprising: a recordable area forinformation having a groove in a first depth being prerecorded with afrequency signal and a land pre-pit address signal from an innercircumference of said information track; a first read only area having apit in a second depth prerecorded with a frequency signal to be recordedwith a reproduction signal as a pit; and a second read only area havinga pit in a first depth prerecorded with a frequency signal and a landpre-pit address signal to be recorded with a reproduction signal as apit, wherein a tracking error signal at a time of tracking off in aboundary between said first read only area and said second read onlyarea is defined as a ratio of maximum amplitude in both directions froma center of maximum amplitude of said tracking error signal at the timeof tracking off in said recordable area.
 2. A reproducing method ofinformation recording medium having an information track formed spirallyor in coaxial circles comprising: a recordable area for informationhaving a groove in a first depth being prerecorded with a frequencysignal and a land pre-pit address signal from an inner circumference ofsaid information track; a first read only area having a pit in a seconddepth prerecorded with a frequency signal to be recorded with areproduction signal as a pit; and a second read only area having a pitin a first depth prerecorded with a frequency signal and a land pre-pitaddress signal to be recorded with a reproduction signal as a pit,wherein a tracking error signal at a time of tracking off in a boundarybetween said first read only area and said second read only area isdefined as a ratio of maximum amplitude in both directions from a centerof maximum amplitude of said tracking error signal at the time oftracking off in said recordable area, said reproducing method comprisingthe steps of: reproducing a land pre-pit address signal of saidinformation track; and tracking said boundary continuously on the basisof amplitude of a tracking error signal in said first read only area andsaid second read only area in accordance with reproduced said landpre-pit address signal.